how to fix P0420 code on Tesla Model S Plaid/Refresh (2021-present)

Learn how to diagnose and fix P0420 exhaust system efficiency issue in Tesla Model S Plaid. Step-by-step guide with diagnostic procedures and repair instructions.

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the vehicle's battery to ensure safety during repair.

2. Inspect and Replace Oxygen Sensors

1. Locate the oxygen sensors: Identify the upstream (pre-cat) and downstream (post-cat) oxygen sensors.
2. Unplug the sensor connectors: Carefully disconnect the electrical connectors from both oxygen sensors.
3. Remove the sensors: Use an oxygen sensor socket to unscrew and remove the sensors from the exhaust system.
4. Install new sensors: Apply anti-seize compound on the threads of the new sensors and install them in the same location as the old ones, tightening them to manufacturer specifications (typically 30-40 ft-lbs).
5. Reconnect the sensor connectors: Ensure the connectors are secured and properly seated.

3. Inspect and Replace Catalytic Converter (if necessary)

1. Remove the exhaust components: If the catalytic converter is damaged, remove any exhaust components obstructing access to it.
2. Unbolt the catalytic converter: Use a socket set to remove the bolts securing the catalytic converter to the exhaust system.
3. Inspect the catalytic converter: Check for signs of clogging or damage; if damaged, replace it with a new unit.
4. Install the new catalytic converter: Position the new catalytic converter and secure it with bolts, tightening to the specified torque (typically 25-30 ft-lbs).
5. Reinstall any removed exhaust components: Ensure all fasteners are tightened and components are properly aligned.

4. Clear Codes and Test Drive

1. Reconnect the battery: Ensure all connections are secure before reconnecting the battery.
2. Clear error codes: Use the OBD-II scanner to clear the P0420 code and any other related codes.
3. Test drive the vehicle: Drive the vehicle under various conditions to ensure the check engine light does not reappear.